Sponsorship of the Oyster system and other sponsorship opportunities could allow Transport for London (TfL) to actively improve stations - introducing free wireless and 4G connectivity, TV screens, lifts, and even toilets for passengers.

While TfL have been staunchly opposed to the sponsorship of stations, GLA Conservatives believe that they haven't been trying hard enough to attract private investment.

With a fare raise expected before the end of the year, such sponsorship could be used to offset ticket hikes, and have companies pay rather than the commuter.

London mayor Boris Johnson was initially hesitant about such commercial deals, but has since been convinced that commercial rebranding of stations is a good idea.

Bacon has also assessed claims from TfL that renaming stations would cost £4m a pop - saying that opposition to sponsored tube station names is "paper thin". Bacon says that changing signage twice cost just £8,500 across the network when Blackfriars was temporarily closed.

While TfL claimed that map reprinting could cost £150,000, Bacon says that when step-free access was introduced, the total cost, including re-design and printing was just £77,295.

Other TfL cost estimates such as £150,000 to update their website (exceeds the TfL's average monthly spend on their journey planner) and £150,000 for the recording of voice announcements (last cost £87,202) are, Bacon says, plucked "from thin air".